Design of WPT System With High Distance-Diameter Ratio Based on Multiple Transmitting Coil Structure

This article presents a high distance-diameter ratio (DDR) wireless power transfer (WPT) system design method. This design method is suitable for different DDRs and transmitting coil gaps. It has the advantage that there is no relay coil on the transmission path which can save space. Higher transmission power and transmission efficiency have been achieved by adjusting the current distribution in each transmitting coil. First, the ratio coefficient of the current in each transmitting coil to the total current is defined and the impact of these coefficients on transmission efficiency is analyzed. Then, a current distribution design method is presented. Based on the optimal current distribution coefficients, the number and gaps of transmitting coils have been designed. Finally, a WPT experimental platform is built. The experimental results indicate that under DDRs of 2, 2.5, and 3, the optimal current distributions can be obtained through the proposed design method, resulting in the highest system transmission efficiency. Additionally, the experimental results show that the transmission efficiency of the designed system is about 6% higher than that of a single transmitting coil system.